Nudists/naturists are just ordinary people and come in all sizes and shapes! Women, especially, being generally more sensitive to their appearance than men (thanks to a bunch of social reasons) tend to be reluctant to bare it all in front of strangers. Poor body image, the scourge of women, simply has no place in social nudism.
In fact, the easy shedding of those fears and concerns about one's body is one of the main reasons women become such enthusiastic fans of naturism! Though hard to believe, most women find it amazingly simple to adjust to social nudity; that's because for perhaps the first time in their lives they are in an environment where beauty and shape are not the basis of how others see them.
There are masses of articles on this subject and we offer some of them here. In most, you will find a similarity as to how nudism not only offers a weekend respite from body image concerns, but carries over into daily life as well.
As we learn to accept and appreciate ourselves as we are, we're less vulnerable to outside influences working to convince us otherwise!
Naked Conversations with Nude Women (2012, 10 minutes, The Netherlands) from Lundoxia on Vimeo.